Pallet/skid power roll system

ABSTRACT

An apparatus moves a plurality of transport media along a path of travel. The plurality of transport media define at least two groups of transport media, where each group of transport media has substantially identical transverse dimensions with respect to one another within one group of transport media, while having substantially different transverse dimensions with respect to another group of transport media. The apparatus includes a plurality of rollers rotatably mounted in fixed locations spaced along a path of travel. At least one motor is provided for driving at least one of the rollers in rotation. At least one transport media is supported on the rollers for movement along the path of travel in response to rotation of the roller by the motor. Each transport media has at least one elongate support member continuously engageable with at least two rollers simultaneously while the transport media moves along the path of travel. A lift workstation can be located along the path of travel for transferring a workpiece carried by one transport media to another transport media.

RELATED APPLICATIONS

[0001] This application is related to a contemporaneously filedapplication entitled TRANSFER MEDIA LIFT EXCHANGE SYSTEM identified asattorneys docket number PTC-301-A.

FIELD OF THE INVENTION

[0002] The present invention relates to a combination power rolltransport system for both skids and pallets, and to a transfer medialift exchange system positionable on opposite longitudinal sides of acombined skid/pallet power roll system.

BACKGROUND OF THE INVENTION

[0003] A pallet can be defined as a precision locating transfer media,such as a geometry fixture, while a skid can be defined as a simpleframe structure transport media not requiring position locating of theworkpiece with respect to the workstation. By way of example and notlimitation, a simple skid frame can be used for supporting a weldedautomotive body for transport through the body undercoating process,while a precision geometry fixture pallet can be provided forpositioning the floor pan, side panels, and roof panels with respect toone another at a welding station location. It would be desirable toprovide an apparatus and method for transporting pallets and skids alonga common portion of an assembly line. It would be desirable to providean apparatus and method for lifting a workpiece from one transport mediain order to place the workpiece on a different transport media.

SUMMARY OF THE INVENTION

[0004] A combined skid/pallet power roll system according to the presentinvention can include a longitudinally extended or enlarged rollerhaving outwardly extending flanges at each end to allow the power rolldrive system to handle either precision geometry fixture pallets ortransportation skids on the same system. The power roll system accordingto the present invention can handle intermixed pallets and skids asrequired for the particular assembly line.

[0005] A transfer media lift exchange system according to the presentinvention can include first and second vertically extending elevators orlifts positioned on opposite longitudinal sides of the combinedskid/pallet power roll system. According to the present invention, thephysical structure of the vertically extending elevator or lift ispowered in synchronized movement with belts extending preferably from asingle drive unit. The lifts on the opposite sides of the power rollconveyor system allow the elevator to engage and lift a workpiece beingconveyed by a skid, pallet, electric monorail system, or versarolloverhead conveyor. Once the workpiece is lifted from the currenttransport media, the current transport media can be removed from theworkstation and a different transport media can be positioned at theworkstation for receiving the workpiece from the elevator or liftassembly. The new transport media can include a different skid, pallet,electric monorail system, or versaroll overhead conveyor as required forthe particular application. In the preferred configuration, the combinedpallet/skid power roll system allows skids and pallets to be transportedthrough the elevator workstation allowing the workpiece to be liftedfrom one skid or pallet for placement on a different pallet or skid asrequired for processing operations downstream of the transport medialift exchange system.

[0006] The present invention can include a “flow through” processconfiguration, where a pallet can be positioned along a pallet transfersystem which transitions into the combined pallet/skid power roll systempassing through the elevator workstation. A workpiece carried by thepallet is lifted from the pallet, and the pallet continues on throughand transfers back to a pallet transfer system from the combined powerroll system. A skid transfer system transitions to the same combinedpallet/skid power roll system for delivering the skid to the elevatorworkstation, where the workpiece has been held after discharging thepallet. The workpiece is then lowered to deliver the workpiece to theskid. The skid then travels out of the elevator workstation andtransitions back to a skid transport system.

[0007] Alternatively, the present invention can include an “in/out”process configuration, where a skid can deliver a workpiece to theelevator workstation, and the combined skid/pallet power roll system ispositioned to receive either skids or pallets. The workpiece carried byskid is lifted from the skid and the skid is removed from the elevatorworkstation by reversing the direction of travel to return to the skidconveyor system. A pallet can then be delivered by a pallet conveyorsystem to the combined skid/pallet power roll system at the elevatorworkstation. The empty pallet can receive the workpiece by the liftassemblies of the elevator being lowered. The loaded pallet can then beremoved from the elevator workstation by reversing the direction oftravel for further movement along the pallet conveyor system.

[0008] Other applications of the present invention will become apparentto those skilled in the art when the following description of the bestmode contemplated for practicing the invention is read in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The description herein makes reference to the accompanyingdrawings wherein like reference numerals refer to like parts throughoutthe several views, and wherein:

[0010]FIG. 1 is a simplified schematic view of a power roll conveyoraccording to the present invention with enlarged rollers of sufficientlongitudinal length to operably engage both pallets and skids havingdifferent transverse dimensions with respect to the path of travel alongthe conveyor;

[0011]FIG. 2 is a simplified perspective view of an elevator or liftworkstation capable of transferring workpieces between differenttransport media;

[0012]FIG. 3 is a side elevational view of the lift workstationillustrated in FIG. 2;

[0013]FIG. 4 is a cross-sectional view of a driven elevator portion ofthe lift workstation taken as shown in FIG. 3;

[0014]FIG. 5 is a cross-sectional view of an idle elevator portion ofthe lift workstation taken as shown in FIG. 3;

[0015]FIG. 6 is a plan view of the lift workstation illustrated in FIGS.2 through 5;

[0016]FIG. 7 is a cross-sectional view of the lift workstation taken asshown in FIG. 3;

[0017]FIG. 8 is a schematic flow diagram illustrating a flow throughconfiguration of the lift workstation illustrated in FIGS. 2 through 7;and

[0018]FIG. 9 is a simplified schematic diagram of an in/out processconfiguration for the lift workstation illustrated in FIGS. 2 through 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] Referring now to FIG. 1, a simplified cross-sectional view of apallet/skid power roll system 10 according to the present invention isillustrated. The pallet/skid power roll system 10 can include a supportframe 12 of any configuration suitable for supporting the loads to betransported along the path of travel and allowing sufficient clearancefor the workpieces to be processed. Suitable support frame structuresare conventional and well known to those skilled in the art. The frame12 can define at least two opposing sidewalls 16, 18 forming a channelor slot therebetween. The opposing sidewalls 16, 18 can be part ofU-shaped channel 20 having a lower wall 22 extending between theopposing walls 16, 18 to define an open upper end extending along theentire longitudinal length of the U-shaped channel 20. The U-shapedchannel 20 can define a path of travel for the pallet/skid power rollsystem 10. A plurality of rollers 24 are rotatably mounted in fixedlocations spaced along the path of travel. At least one motor 26 isprovided for driving at least a portion of the plurality of rollers 24in rotation. The transport media 28, such as a pallet and/or a skid, issupported on the plurality of rollers 24 for movement along the path oftravel in response to rotation of the driven rollers 24 by the motor 26.Each transport media 28 has at least one elongate support member 30extending along at least a portion of the longitudinal length of thetransport media 30 between the upstream end and the downstream end ofthe transport media 30. The at least one elongate support member 30 iscontinuously engagable with at least two rollers 24 simultaneously whilethe supported transport media 28 moves along the path of travel.Typically, if the transport media 28 is a geometry fixture pallet, apair of transversely spaced support members 30 are continuouslyengagable with transversely spaced rollers 24 driven by the motor 26.The transverse spacing of the two transversely spaced elongate supportmembers 30 p of the pallet are typically further apart then thetransverse spacing of the two elongate support members 30 s of acorresponding transport skid. The plurality of rollers 24 are elongatedalong the longitudinal axis of rotation to support the correspondingelongate support members 30 p, 30 s in order to allow powered movementof pallets and/or skids along the power roll system 10. Each roller 24includes outer enlarged ends or flanges 23, 25 to help maintain thetransport media 28 in a centered position with respect to the path oftravel along the power roll system 10.

[0020] The plurality of rollers 24 of an individual frame 12 can beoperably associated with respect to one another to rotate substantiallyin unison if desired. The power roll system 10 according to the presentinvention can include a plurality of belts 42, 42 a, 44, 44 a foroperably associating adjacent rollers with respect to one another. Itshould be recognized that the plurality of belts can be replaced with asingle belt, a chain, or any other suitable drive mechanism for rotatingone or more of the rollers in response to rotation of the motor. Themotor 26 can be either rotatable in a single direction for use in a passthrough configuration as illustrated in FIG. 8, or can be a reversiblemotor for use with the in/out configuration illustrated in FIG. 9.

[0021] Each roller 24 can be operably connected to a pulley 32 forrotation about an axis defined by shaft 36. Shaft 36 can be supported byopposing walls 16, 18 of the open top U-shaped channel 20. A cover canbe provided for enclosing a substantial portion of the open top U-shapedchannel 20 while allowing the upper portion of each roller 24 to extendthrough the cover for engagement with the elongate support members 30 ofeach transport media 28. The motor 26, through an appropriate gear boxor transmission 40, drives at least one of the rollers 24. The firstpulley 32 can be operably associated with a first drive belt 42. Thefirst pulley 32 can be driven by the motor 26 and transfer rotationalmotion to an adjacent, second pulley spaced longitudinally from thefirst pulley with respect to the path of travel. A second drive belt canbe extended from the second pulley for engagement with a third pulleyspaced further longitudinally from the drive motor 26 than the secondpulley. The series of interconnected first and second drive belts extendbetween adjacent roller assemblies to operably engage with correspondingdrive pulleys to transfer the rotational motion of the motor 26 along atleast a portion or segment of the path of travel of the power rollconveyor system 10 according to the present invention. Preferably, themotor 26 is a variable frequency reversible drive capable oftransporting a transport media 28 at the desired speed when loaded witha workpiece to be conveyed along the path of travel. One or more motors26 can be disposed along the longitudinal length of the path of travelfor separate independent control of the transport media 28 as thetransport media 28 moves between one or more workstations located alongthe path of travel. A lift workstation 46 can be provided along the pathof travel of the power roll conveyor system 10. It should be recognizedthat the lift workstation 46 can be used in combination with a powerroll conveyor system 10, and/or a pallet conveyor system, and/or a skidconveyor system, and/or an electric monorail conveyor system, and/or aversaroll overhead conveyor system such as that disclosed in U.S. patentapplication Ser. No. 10/225,291, filed Aug. 22, 2002 (attorney docketnumber PTC-283-C) which is incorporated by reference herein in itsentirety. The variable frequency drive motor 26 for this segment of thepower roll conveyor system 10 can be controlled by a controller 48schematically illustrated in FIG. 3 in response to one or more sensors50. The sensors 50 can be positioned at floor level along with anycontrol panel required for the controller 48 for ease of maintenance.The sensors 50 can be positioned adjacent the entry to the workstation46 for signaling the controller 48 to slow the variable frequency drivemotor 26 as the transport media 28 enters the workstation 46. Additionalsensors can be appropriately positioned in order to accurately stop thetransport media 28 at the desired position at the lift workstation 46.

[0022] The lift workstation 46 can best be seen in FIGS. 2 through 7.Each vertically extending side 52, 54 of the lift workstation 46supports a corresponding vertically reciprocal lift carriage 56, 58.Each lift carriage 56, 58 includes a plurality of guide rollers 60engagable with surfaces of the vertically extending sides 52, 54 formaintaining the orientation of the reciprocal lift carriages 56, 58during movement between a raised position and a lowered position. Eachlift carriage 56, 58 includes a rigid frame 62 supporting the guiderollers 60 and further supporting inwardly extending cantilevered liftarms 64. The lift arms 64 are capable of operably engaging a workpiececarried by the transport media 28 in order to lift the workpiece fromone transport media 28 for delivery to another transport media to bedelivered to the lift workstation 46.

[0023] In the illustrated configuration, by way of example and notlimitation, one of the lift carriages is a driven elevator 56, while theother lift carriage is an idler elevator 58. A single lift motor 66 canbe provided for lifting both the driven elevator 56 and idler elevator58 through an appropriate gear box or transmission 68. The rotation ofthe lift motor 66 can be transferred to the driven elevator by one ormore lift belts 70 while simultaneously being transferred to the idlerelevator 58 by one or more belts 72. Movement of the idler lift belt 72can occur either directly from engagement with the drive portion of thesingle lift motor 66, or can be operably connected through appropriateidler pulleys to move synchronously with the driven elevator in responseto motion of the driven elevator by the single lift motor 66. A singledrive motor is used in the preferred configuration in order to simplifythe synchronous movement of opposite sides of the vertically reciprocallift carriages 56, 58 in order to maintain the workpiece in a balanceconfiguration without requiring complicated synchronization controls formultiple drive motors.

[0024] In operation, the controller 48 at the lift station 46 issignaled that a workpiece has been delivered by activation of sensor 50.When the workpiece is located at the ready position, the sensor 50signals the controller 48, and the controller 48 actuates the singlelift motor 66 to move the lift carriages 56, 58 simultaneously from thelowered position to the raised position in order to remove the workpiecefrom the transport media 28, such as a pallet, a skid, or an overheadcarriage connected to an electric monorail system or versaroll overheadconveyor system. After reaching the raised position with the workpiece,the single lift motor 66 is stopped, and the transport media 28 isremoved from the lift workstation 46. Another transport media 28, suchas a pallet, a skid, or a carriage connected to an electric monorailconveyor system or versaroll overhead conveyor system, is delivered tothe lift workstation 46. When the second transport media 28 had beendelivered to the lift workstation 46, the sensor 50 signals thecontroller 48 to actuate reversal of the single lift motor 66 in orderto lower the workpiece with the vertically reciprocal lift carriages 56,58. When the lift carriages 56, 58 reach the lowered position, theworkpiece is transferred to the new transport media 28 located at thelift workstation 46.

[0025] Referring now to FIG. 8, a pass through configuration for thevertical lift station 46 using the pallet/skid power roll system 10according to the present invention is illustrated. In thisconfiguration, a pallet or skid transport system 80 delivers a workpieceloaded on a pallet or skid to the workstation 46. The workpiece isremoved from the pallet or skid at the lift workstation 46 as describedin greater detail above. After the workpiece has been removed from thepallet or skid, the empty pallet or skid passes through the workstationand is transferred back to the return line of the pallet or skidtransport system 82. An empty skid or pallet is delivered to theworkstation 46 by a skid or pallet delivery system 84. The workpieceheld by the raised lift carriages 56, 58 is lowered and the workpiece istransferred to the empty skid or pallet as described in greater detailabove. After the workpiece has been loaded on the skid or pallet, theskid or pallet passes through the lift workstation 46 and continues tothe loaded skid or pallet transport system 86.

[0026] Referring now to FIG. 9, an alternative in/out configuration ofthe lift workstation 46 and pallet/skid power roll system 10 accordingto the present invention is schematically illustrated. In thisconfiguration, the loaded skid or pallet is delivered to the workstation46 by media transport system 88. At the left workstation 46, the liftcarriages 56, 58 are raised in order to remove the workpiece from theloaded pallet or skid. The empty pallet or skid is then removed from thelift workstation 46 by reversing out of the workstation to continuealong the pallet or skid transfer system 90. An empty skid or pallet isdelivered to the workstation 46 by media transport system 92. Theworkpiece is loaded on the empty pallet or skid as described in greaterdetail above. The loaded pallet or skid is then reversed out of theworkstation 46 for continue transportation on the pallet or skidtransportation system 94.

[0027] It should be recognized that the pallet/skid power roll systemand lift workstation disclosed according to the present invention can beused independently of one another, or in any desired combination inorder to allow the flexible delivery and transfer from one transportmedia to another transport media. The delivering transport media caninclude a pallet, a skid, an overhead carriage, such as a carriageconnected to an electric monorail system or versaroll overhead system.The removing transport media can include a different transport media ora similar transport media, and can be selected from a pallet, a skid, anoverhead carriage, such as a carriage connected to an electric monorailsystem, or a versaroll overhead conveyor system. The present inventionpermits the transfer of workpieces from various transport media in asimple and efficient fashion. Further, the pallet/skid power roll systemaccording to the present invention allows the delivery and removal ofeither pallets or skids along the same section of the conveyor systempermitting simplified conversion from pallet delivery to skid delivery,or skid delivery to pallet delivery as required for the particularapplication.

[0028] While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims, which scope is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructures as is permitted under the law.

What is claimed is:
 1. An apparatus for moving a plurality of transportmedia along a path of travel, the plurality of transport media definingat least two groups of transport media, each group of transport mediahaving substantially identical transverse dimensions with respect to oneanother within one group of transport media, while having substantiallydifferent transverse dimensions with respect to another group oftransport media, the apparatus comprising: a plurality of rollersrotatably mounted in fixed locations spaced along a path of travel; atleast one motor for driving at least one of the rollers in rotation; andat least one transport media supported on the rollers for movement alongthe path of travel in response to rotation of the roller by the motor,each transport media having at least one elongate support membercontinuously engageable with at least two rollers simultaneously whilethe transport media moves along the path of travel.
 2. The apparatus ofclaim 1 further comprising: a frame for supporting the plurality ofrollers operably engagable with the transport media for movement of thetransport media along the path of travel.
 3. The apparatus of claim 1further comprising: each roller of sufficient dimension to operablyengage and support both groups of transport media for movement along thepath of travel.
 4. The apparatus of claim 1 further comprising: eachroller operably connect to a common shaft with a driven pulley and adriving pulley; and a plurality of elongate drive members engagedbetween adjacent rollers connecting the driven pulley of one roller withthe driving pulley of an adjacent roller for transmitting rotation fromthe motor to the plurality of rollers along the path of travel.
 5. Theapparatus of claim 1, wherein the plurality of rollers further comprise:a first set of rollers rotatably driven to move the transport mediaalong the path of travel; and a second set of rollers freely rotatableto support the transport media during movement along the path of travel.6. The apparatus of claim 5, wherein a first roller of the first set ofrollers and a second roller of the second set of rollers arepositionable along a common axis extending transverse to the path oftravel.
 7. The apparatus of claim 1 further comprising: at least onesensor for sensing a position of the transport media along the path oftravel and for emitting a signal; and control means for receiving thesignal from the at least one sensor and for controlling the motorrotating the plurality of rollers in response to the signal.
 8. Theapparatus of claim 1 further comprising: means for moving the elongatemember between a first section of the path of travel and a secondsection of the path of travel, where the first and second sections ofthe path are at an angular, non-linear, orientation with respect to oneanother.
 9. The apparatus of claim 1 further comprising: a liftworkstation located along the path of travel; and at least one sensoroperably positionable for sensing the transport media when at the liftworkstation for controlling movement of the transport media at the liftworkstation as the transport media is driven along the path of travel byrotation of the plurality of rollers.
 10. The apparatus of claim 1further comprising: a lift workstation located along the path of travelfor transferring a workpiece carried by one transport media to anothertransport media.
 11. The apparatus of claim 10, wherein the liftworkstation further comprises: at least two vertically extending framemembers positioned on opposite sides of the path of travel at the liftworkstation; and reciprocal means moveable vertically along thevertically extending frame members for lifting a workpiece from onetransport media and for delivering the lifted workpiece to anothertransport media.
 12. The apparatus of claim 11, wherein the reciprocallifting means further comprises: first and second elevators connected tothe vertically extending frame members positioned on opposite sides ofthe path of travel at the lift workstation.
 13. The apparatus of claim12 further comprising: a plurality of guide rollers supported on each ofthe first and second elevators for operable engagement with surfaces ofthe frame members for guiding reciprocal movement of the elevatorsbetween a lowered position and a raised position.
 14. The apparatus ofclaim 13 further comprising: at least one motor operably connected tothe first and second elevators for moving the elevators between thelowered position and the raised position.
 15. The apparatus of claim 14further comprising: at least one drive belt extending between the atleast one motor and the first and second elevators for moving theelevators in response to operation of the motor.
 16. The apparatus ofclaim 14 further comprising: control means for operating the at leastone motor in response to arrival and departure of transport media to thelift workstation; and a sensor for sensing whether a transport media islocated in a ready position at the lift workstation, and for generatinga signal corresponding to a sensed condition of the transport media. 17.The apparatus of claim 1 wherein the transport media is selected from agroup consisting of a geometry fixture, a pallet, a skid, and anoverhead carriage.
 18. A method for moving a plurality of transportmedia along a path of travel, the plurality of transport media definingat least two groups of transport media, each group of transport mediahaving substantially identical transverse dimensions with respect to oneanother within one group of transport media, while having substantiallydifferent transverse dimensions with respect to another group oftransport media, the method comprising the steps of: supporting at leastone transport media on a plurality of rollers rotatably mounted in fixedlocations spaced along a path of travel; driving at least one of therollers in rotation with at least one motor; and moving the at least onetransport media supported on the rollers along the path of travel inresponse to rotation of the roller by the motor, each transport mediahaving at least one elongate support member continuously engageable withat least two rollers simultaneously while the transport media movesalong the path of travel.
 19. The method of claim 18 further comprisingthe steps of: delivering a workpiece to a lift station with a firsttransport media; lifting the workpiece from the first transport mediawith reciprocal elevators; passing the empty first transport mediathrough the lift workstation; delivering an empty second transport mediato the lift workstation; loading the lifted workpiece on the secondtransport media with the reciprocal elevators; and passing the loadedsecond transport media through the lift workstation.
 20. The method ofclaim 18 further comprising the steps of: delivering a workpiece to alift station with a first transport media; lifting the workpiece fromthe first transport media with reciprocal elevators; reversing movementof the empty first transport media to remove the empty first transportmedia from the lift workstation; delivering an empty second transportmedia to the lift workstation; loading the lifted workpiece on thesecond transport media with the reciprocal elevators; and reversingmovement of the loaded second transport media to remove the loadedsecond transport media from the lift workstation.